The invention refers to a device for milling off ground surfaces, especially roadways.
Such devices are also called front loader milling machines. Such a front loader milling machine is known from DE 39 03 482 A1, for example. The known milling machines have a self-propelled track assembly with a pair of front wheels and a pair of rear wheels. The track assembly carries a machine frame in which a milling roll is supported transverse to the direction of motion. In order to transport away possibly all of the milled off material, the milling roll is generally enclosed by a casing where the wall directed in the traveling direction is designed as a covering shield with a passage opening for the milled off material. The material worked off by the milling roll is thrown onto a first conveyor belt by the milling roll, the band conveying the worked off material onto a discharge band at the end of the milling machine, which discharge band can be tilted and pivoted to the sides for discharge onto the floor of a truck.
The milling roll is equipped with chiseling tools forming a conveyor helix that transports the milled off material to the passage opening of the covering shield.
The first conveyor belt in front of the milling roll is easily damaged by breaking ground plates, the repair of the conveyor belt requiring the disassembly of the conveying means. Disassembling and mounting the conveying means is rather troublesome and time-consuming. Moreover, several people are needed for this work.
It is the object of the invention to develop a device of the type mentioned above such that the risk of troubles is substantially reduced.
Advantageously, the invention provides that the end of the conveying means at the milling roll is supported in a belt shoe mounted for vertical adjustment at the machine frame, and that the belt shoe and the conveying means form a rigid unit that cannot be pivoted in relation to each other. The belt shoe and the conveying means can thus not move relative to each other, whereby no worked off material can get jammed between the belt shoe and the conveying means. In this manner, the risk of trouble that would require the disassembly of the conveying means is reduced substantially. The belt shoe is pivoted relative to the machine frame together with the rear end of the conveying means supported in the shoe.
Preferably, the conveying means is removably supported in the rear part of the belt shoe facing the milling roll, the position of the belt shoe relative to the conveying means being fixed by the support of the conveying means and by at least one connecting strut between the belt shoe and the conveying means. The connecting strut makes sure that the belt shoe cannot move in relation to the conveying means.
At least one piston-cylinder unit is provided a lifting means between the machine frame and the belt shoe. By means of this piston-cylinder unit, the belt shoe can be lifted vertically to surmount obstacles, for example. The piston-cylinder unit cannot push the belt shoe down, but only lift it when desired. Furthermore, the belt shoe can move up freely together with the conveying means.
In a preferred embodiment, it is provided that upon vertical adjustment, two hingedly connected connecting rods guide the belt shoe with the rear end of the conveying means, the first connecting rod being hinged to the belt shoe and the second connecting rod being hinged to the machine frame. When lifting the belt shoe, the connecting rods provide for an exact guiding of the unit formed by the belt shoe and the conveying means. Here, the unit is pivoted about the bearing point of the conveying means in the shaft of the machine frame.
Preferably, it is provided that the connecting rods and/or the connecting strut are arranged on both sides of the belt shoe. The double arrangement of the connecting rods and the connecting strut on both sides of the belt shoe causes an exact guiding of the rear end of the conveying means and the belt shoe along a predetermined path. The double arrangement of the connecting strut increases the torsional rigidity of the unit formed by the belt shoe and the conveying means.
With connecting rods supported on both sides of the machine frame, it is preferably provided that the connecting rods hinged to the machine frame are coupled via a linking rod. The linking rod synchronizes the movement of the connecting rods on both sides so that an exact parallel guiding of the belt shoe with the rear end of the conveying means is guaranteed.
The connecting rod may be bent like a toggle lever, the linking rod being supported in the toggle portion. Supporting the linking rod in the toggle portion improves the force transmission because of the leverage.
The belt shoe is provided with a transverse protective shield for protecting the conveyor belt of the conveying means. The protective shield prevents sharp-edged material from damaging the conveyor belt.
The roll casing has stops for the lowest and/or frontmost position of the belt shoe. The stop for the lowest position of the belt shoe limits the downward pivoting movement of the unit formed by the belt shoe and the rear end of the conveying means. A further stop for the frontmost position of the belt shoe prevents collision with the roll casing. Nevertheless, it is possible to lift the belt shoe for up to 300 mm from the lowest position, the belt shoe and the conveying means being only slightly pivoted.
The bottom surface of the belt shoe is formed by a grid of a plurality of grid bars extending parallel to the traveling direction. The grid simultaneously serves as a holding-down means and a sliding shoe.
Preferably, it is provided that a holding-down means is respectively provided on both sides of the belt shoe at the edge facing the milling roll so that the belt shoe extends over the entire width of the milling roll.
The following is a detailed description of an embodiment of the invention with reference to the accompanying drawings.